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Re: How many times does it crank? Maybe I'm just Posted by Ari [Email]  (#2847) [Profile/Gallery]
(more from Ari) on Tue, 1 Nov 2005 05:37:46
In Reply to: How many times does it crank? Maybe I'm just, Noel, Tue, 1 Nov 2005 05:17:49 Members do not see ads below this line. - Help Keep This Site Online - Signup |
Please don't take this the wrong way, but you might just be obsessing.
The number of cranks the engine takes to catch will depend on how fast fuel comes to pressure, how fast the engine is turning, where it stopped in the 2-rotation cycle, the compression ratio of the engine, plugs, phase of the moon and latest sports scores.
I doubt it's DI - it either sparks or it doesn't. And when starting, it sparks like mad.
There is an anti-drain valve back at the pump, and if that leaks down fast, it'll take a little bit longer to get to full pressure. The FPR really doesn't have much to do with it; it simply limits full pressure. Compression is a big one - without enough 'squeeze', the air/fuel mixture won't burn. Even a subtle change in engine crank speed will impact effective compression, and then there is actual compression due to leaky valves and such. And as a battery ages, or the starter gets old, or the oil is colder, there will be a slightly lower cranks speed.
Compression may increase or decrease as a car ages; it tends to drop because things loosen up; it tends to increase due to carbon buildup. Which wins out? Depends on the car.
So just like people, cars take a bit longer to get going as they age. Some may start faster if their compression is increasing.
It's always good to monitor your car, get to know it, and spot trends early. At the same time, we can all start to focus in too closely on those things we can monitor because we can count or there is a gauge for it - (Geeze! My cranking voltage is 0.1 volts lower today, and my idle voltage is down 0.2! Buy a new alternator!)
If it's taking longer to start, I'd suspect the battery. And if it's just a little bit slower over a long period of time (years), then it's just getting old. And comparing it to another car is cheating. Each car is a little bit different when it leaves the factory, and those little differences only get bigger as cars age.
posted by 192.249....
, Tue, 1 Nov 2005 11:17:27, Tue, 1 Nov 2005 05:37:46 <-- Viewing This Message
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